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33 lines
1.2 KiB
33 lines
1.2 KiB
//! Example of limiting a WebAssembly function's runtime using "fuel consumption".
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// You can execute this example with `cargo run --example fuel`
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use wasmtime::*;
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fn main() -> Result<()> {
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let mut config = Config::new();
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config.consume_fuel(true);
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let engine = Engine::new(&config)?;
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let mut store = Store::new(&engine, ());
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store.set_fuel(10_000)?;
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let module = Module::from_file(store.engine(), "examples/fuel.wat")?;
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let instance = Instance::new(&mut store, &module, &[])?;
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// Invoke `fibonacci` export with higher and higher numbers until we exhaust our fuel.
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let fibonacci = instance.get_typed_func::<i32, i32>(&mut store, "fibonacci")?;
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for n in 1.. {
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let fuel_before = store.get_fuel().unwrap();
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let output = match fibonacci.call(&mut store, n) {
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Ok(v) => v,
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Err(e) => {
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assert_eq!(e.downcast::<Trap>()?, Trap::OutOfFuel);
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println!("Exhausted fuel computing fib({})", n);
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break;
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}
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};
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let fuel_consumed = fuel_before - store.get_fuel().unwrap();
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println!("fib({}) = {} [consumed {} fuel]", n, output, fuel_consumed);
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store.set_fuel(10_000)?;
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}
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Ok(())
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}
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